Facial expressions do vary across cultures, despite the assumption of universality. Arabs do not frown, but jerk their heads up when angry. East Asians have nuanced expressions that Westerners do not notice. Eye contact is considered rude in some cultures. Anglo-based cultures avoid moving their upper lip as much as possible. Most Americans I tell this to get very angry, because it seems to violate the cultural principle of universality.

However, there are some interesting generalities that apply across cultures — lower class people tend to open their mouths and eyes wider. People from rural backgrounds (regardless of country) tend to have weird, non-standard facial expressions, possibly because of greater isolation from mass media. Some individuals laugh without changing their facial expression — this seems to occur randomly.